In medical emergencies and even in routine care it is often necessary to transport a patient from the location of the accident or injury to a place of medical care. This transport can take place in several stages, often starting with hand carrying by medical workers, then transitioning to a ground or air vehicle. During these different modes of transport, the patient must be secured under varying types of accelerations and loading. The types of loading include both handling loads and vehicle accelerations. During transport by hand, the loads are typically vertical and lateral jostling with the loads being supported at the litter handles. During transport by vehicle, the highest loads are forward and lateral generated by vehicle accidents with the loads being supported by the litter-to-vehicle restraints.
In addition to supporting the weight of the patient and the associated medical gear through the transportation loads, the litter must fold compactly when it is not being used. Current litter technology is based on frame structures. Frame structures are structures in which the majority of the loads are carried through bending of local components. These bending loads result in local stress concentrations which must be accommodated with additional structural material, resulting higher overall litter weight.
The military has long used the foldable “Talon” litter which includes two spaced foldable longerons supporting a bed and interconnected by foldable bars. Because such a litter is based on a framed structure, it is relatively heavy. Moreover, in testing, the litter fails when subject to high accelerations. Various other litter designs are shown in U.S. Patent Application and Publication Nos. U.S. 2010/0138999; U.S. Pat. Nos. 3,886,606; 6,842,923; 7,043,785; 2,360,371; and 3,555,578 all incorporated herein by this reference.